The invention relates to a method for producing a workpiece in the form of a metal sheet with at least one at least partly rolled edge, the at least one edge to be rolled having a curvature in at least one portion.
The invention also relates to a workpiece produced according to the abovementioned method in the form of a metal sheet having at least one at least partly rolled edge.
It is known to roll edges of metal sheets, for example in order to obtain a reinforced margin of the metal sheet, or in order to produce, for example, a hinge lug on the metal sheet.
To roll an edge of the workpiece in the form of a metal sheet, the workpiece is put into a special rolling tool which has a tool top part and a tool bottom part. The tool top part and the tool bottom part are movable relative to one another. In one of the two tool parts, there is a hollow in the shape of a circle segment in cross section, into which the workpiece, with the edge to be rolled at the front, is pressed by the relative movement between tool bottom part and tool top part. When the edge continues to be pressed into the circle-segment-shaped hollow, the edge rolls along the inner wall of the circle-segment-shaped hollow. The edge may be rolled, for example, only partly, for example over a rolling angle of 90° to 180°, or beyond 180° until a rolling angle of almost 360° is achieved, i.e. until the edge is rolled completely.
The workpieces that can be rolled are not only those whose edge to be rolled is straight but also those whose edge to be rolled has a curvature in at least one section, which also includes the case where the edge to be rolled has a curvature or bend over its entire length to be rolled.
In the case of sheet metal edges which have such a curvature, it has been found that an undesirable kink is produced in the region of the curvature during the rolling of the edge, i.e. the workpiece has a kink in the rolled margin in the region of the curvature after the rolling of the edge, and this kink prevents or even completely rules out the usefulness of the workpiece for the subsequent purpose, for example as a component in the motor vehicle industry. Such a kink can impair not only the aesthetic appearance of the workpiece produced in this way but also its strength or stability, since the kink produced can become greater during loading or stressing of the workpiece.